Selective activation and inhibition of calmodulin-dependent enzymes by a calmodulin-like protein found in human epithelial cells.

Published

Journal Article

A calmodulin-like protein, which is identical in size and 85% identical to vertebrate calmodulin, was recently identified by 'subtractive hybridization' comparison of transcripts expressed in normal versus transformed human mammary epithelial cells. Unlike the ubiquitous distribution of calmodulin, calmodulin-like protein expression is restricted to certain epithelial cells, and appears to be modulated during differentiation. In addition, calmodulin-like protein levels are often significantly reduced in malignant tumor cells as compared to corresponding normal epithelial cells. The current studies compare calmodulin-like protein functions with those of calmodulin. We find that calmodulin-like protein activation of multifunctional Ca2+/calmodulin-dependent protein kinase II (calmodulin kinase II) is equivalent to activation by calmodulin, but that four other calmodulin-dependent enzymes, cGMP phosphodiesterase, calcineurin, nitric-oxide synthase, and myosin-light-chain kinase, display much weaker activation by calmodulin-like protein than by calmodulin. In the case of myosin-light-chain kinase, calmodulin-like protein competitively inhibits calmodulin activation of the enzyme with a Ki value of 170 nM. Thus, calmodulin-like protein may have evolved to function as a specific agonist of certain calmodulin-dependent enzymes, and/or as a specific competitive antagonist of other calmodulin-dependent enzymes.

Full Text

Duke Authors

Cited Authors

  • Edman, CF; George, SE; Means, AR; Schulman, H; Yaswen, P

Published Date

  • December 1994

Published In

Volume / Issue

  • 226 / 2

Start / End Page

  • 725 - 730

PubMed ID

  • 7528142

Pubmed Central ID

  • 7528142

Electronic International Standard Serial Number (EISSN)

  • 1432-1033

International Standard Serial Number (ISSN)

  • 0014-2956

Digital Object Identifier (DOI)

  • 10.1111/j.1432-1033.1994.tb20101.x

Language

  • eng